拡張機能の例
======

拡張機能の開発方法を分かりやすく説明するため、シンプルな拡張機能のサンプルを集めたリポジトリ https://github.com/mdn/webextensions-examples を公開しています。この記事では、そのリポジトリで使われている WebExtension API について説明します。

これらのサンプルは Firefox Nightly で動作します。ほとんどのものがより早期の Firefox でも動作しますが、拡張機能の manifest.json に指定されている `strict_min_version` キーを確認してください。

**警告:** いくつかの例では、特定のドメインまたはページでのみ動作します。制限事項の詳細は、各サンプルの readme ファイルに記載されています。どの例も既定ではプライベートブラウジングウィンドウでは動作しません。詳細は「プライベートブラウジングでの拡張機能」をご覧ください。

これらの例を試してみる場合は、リポジトリをクローンしてから下記のようにしてください。

1. 一時的なアドオンを読み込む (Load Temporary Add-on) 機能を使用する。拡張機能は Firefox を再起動するまで読み込まれたままになります。
2. コマンドラインで拡張機能のソースフォルダーを開き、 web-ext を使用して拡張機能を実行する。拡張機能は Firefox を再起動するまで読み込まれたままになります。
3. Firefox で **ファイル** > **ファイルを開く** を使用し、 build フォルダーにある例を探す。 `build` フォルダーにはビルドされ署名されたバージョンのすべての例が置いてあります。これは例を永続的にインストールします。

**警告:** この例の WebExtension を addons.mozilla.org (AMO) に投稿しないでください、WebExtension の例を実行するのに署名をする必要はありません。単に上記の手順に従ってください。

リポジトリに貢献したい方は、是非とも pull request を送ってください！

| Name | Description | JavaScript APIs |
| --- | --- | --- |
| annotate-page | Displays a sidebar that lets you take notes on web pages. | `storage.local``tabs.onActivated``tabs.onUpdated``tabs.query``tabs.Tab``windows.getCurrent``windows​.Window` |
| apply-css | Adds a page action to the toolbar. Click the button to apply a red border using injected CSS. Click the button again to remove the CSS. | `pageAction.getTitle``pageAction.onClicked``pageAction.setIcon``pageAction.setTitle``pageAction.show``tabs.insertCSS``tabs.onUpdated``tabs.query``tabs.removeCSS``tabs.Tab` |
| beastify | Adds a browser action icon to the toolbar. Click the button to choose a beast. The active tab's body content is then replaced with a picture of the chosen beast. | `extension.getURL``runtime.onMessage``tabs.executeScript``tabs.insertCSS``tabs.query``tabs.removeCSS``tabs.sendMessage``tabs.Tab` |
| bookmark-it | Adds a bookmark button to the toolbar. Click the button to toggle a bookmark for the current page. | `bookmarks.create``bookmarks.onCreated``bookmarks.onRemoved``bookmarks.remove``bookmarks.search``browserAction.onClicked``browserAction.setIcon``browserAction.setTitle``tabs.onActivated``tabs.onUpdated``tabs.query``tabs.Tab``windows.onFocusChanged` |
| borderify | Adds a solid red border to all webpages matching mozilla.org. |  |
| chill-out | Show a page action after a period of inactivity. Show cat gifs when the page action is clicked. | `alarms.clearAll``alarms.create``alarms.onAlarm``pageAction.hide``pageAction.onClicked``pageAction.show``tabs.get``tabs.onActivated``tabs.onUpdated``tabs.query``tabs.update` |
| commands | Demonstrates using the commands API to set up a keyboard shortcut. The shortcut created is accessed using Ctrl+Shift+U (Command+Shift+U on a Mac). | `commands.getAll``commands.onCommand``commands.reset``commands.update``tabs.create` |
| content-script-register | Illustrates how an extension can register URL-matching content scripts at runtime. | `contentScripts.register``runtime.onMessage``runtime.sendMessage` |
| context-menu-copy-link-with-types | Add a context menu option to links to copy the link to the clipboard, as plain text and as a link in rich HTML. | `contextMenus.create``contextMenus.onClicked``tabs.executeScript` |
| contextual-identities | List, create, and remove contextual identities. | `contextualIdentities.query``tabs.create``tabs.query``tabs.remove` |
| cookie-bg-picker | Allows the user to customize the background color and tiled pattern on sites they visit, and also saves their preferences via a cookie, reapplying them whenever they revisit a site they previously customized. | `cookies.get``cookies.onChanged``cookies.remove``cookies.set``extension.getURL``runtime.onMessage``tabs.onActivated``tabs.onUpdated``tabs.query``tabs.Tab``tabs.sendMessage` |
| devtools-panels | Demonstrates some of the devtools APIs. | `devtools.inspectedWindow``devtools.panels``runtime.getURL``runtime.onMessage``runtime.sendMessage``tabs.executeScript` |
| discogs-search | Demonstrates adding a custom search engine with the chrome\_settings\_overrides key. |  |
| dnr-block-only | Demonstrates how to block network requests without host permissions using the declarativeNetRequest API with the `declarative\_net\_request` manifest key. | `declarativeNetRequest.Rule``declarativeNetRequest.RuleAction``declarativeNetRequest.RuleCondition` |
| dnr-dynamic-with-options | Demonstrates a generic way to request host permissions and register declarativeNetRequest rules to modify network requests, without any install-time permission warnings. The options\_ui page offers a way to request permissions and register DNR rules. | `declarativeNetRequest.Rule``declarativeNetRequest.getDynamicRules``declarativeNetRequest.getSessionRules``declarativeNetRequest.updateDynamicRules``declarativeNetRequest.updateSessionRules``permissions.getAll``permissions.remove``permissions.request` |
| dnr-redirect-url | Demonstrates multiple ways to redirect requests using the declarativeNetRequest API through the `declarative\_net\_request` manifest key. Demonstrates aspects of Manifest Version 3 (MV3): action, host\_permissions, and web\_accessible\_resources, and includes a comparison with Manifest Version 2 (MV2). | `declarativeNetRequest.Redirect``declarativeNetRequest.Rule``declarativeNetRequest.RuleAction``declarativeNetRequest.RuleCondition``declarativeNetRequest.URLTransform``permissions.contains``permissions.remove``permissions.request` |
| dynamic-theme | Dynamic theme example | `alarms.create``alarms.onAlarm``theme.update` |
| emoji-substitution | Replaces words with emojis. |  |
| eslint-example | Demonstrates how to configure an extension with eslint. |  |
| export-helpers | Demonstrates how to use export helpers like cloneInto to share objects with page scripts. | `notifications.create``runtime.onMessage``runtime.sendMessage` |
| favourite-colour | An example options page, letting you store your favourite colour. | `browserAction.onClicked``runtime.openOptionsPage``storage.managed``storage.sync` |
| find-across-tabs | Demonstration of the find API. | `browserAction.onClicked``extension.getBackgroundPage``find.find``find.highlightResults``runtime.getURL``runtime.onMessage``runtime.sendMessage``tabs.create``tabs.query``tabs.Tab` |
| firefox-code-search | Demonstrates how to use the omnibox API. | `omnibox.onInputChanged``omnibox.onInputEntered``omnibox.setDefaultSuggestion``tabs.create``tabs.update` |
| forget-it | Demonstrates how to use the browsingData API. | `browserAction.onClicked``browsingData.remove``notifications.create``storage.local` |
| google-userinfo | Demonstrates how to use the identity API. | `browserAction.onClicked``identity.getRedirectURL``identity.launchWebAuthFlow``notifications.create` |
| history-deleter | History API demo: deletes history items for a given domain | `history.deleteUrl``history.search``pageAction.show``tabs.onUpdated``tabs.query` |
| http-response | Demonstrates how to rewrite HTTP responses using the webRequest.filterResponseData() API. | `webRequest.filterResponseData``webRequest.onBeforeRequest` |
| imagify | Using a sidebar, illustrates the use of file picker and drag and drop. A content script replaces the current page content with the chosen image. | `extension.getURL``runtime.onMessage``tabs.executeScript``tabs.query``tabs.sendMessage` |
| latest-download | Shows the last downloaded item, and lets you open or delete it. | `downloads.erase``downloads.getFileIcon``downloads.open``downloads.removeFile``downloads.search` |
| list-cookies | This extensions list the cookies in the active tab. | `cookies.getAll``tabs.query` |
| menu-accesskey-visible | Shows how to set up a single letter access key for a menu item. | `i18n.getMessage``menus.update``menus.create``menus.onClicked` |
| menu-demo | Demonstrates adding and manipulating menu items using the menus API. | `i18n.getMessage``menus.create``menus.onClicked``menus.remove``menus.update``runtime.lastError``tabs.executeScript` |
| menu-labelled-open | Shows how an extension can listen for the display of a menu and then add, remove, or update its menu items. | `menus.create``menus.onClicked``menus.onShown``menus.refresh``menus.update``tabs.update` |
| menu-remove-element | Shows how to detect the page element at the cursor position and remove that element, or a parent element, from the page. This example includes use of the polyfill, illustrating cross-browser extension development. | `menus.create``menus.onClicked``menus.getTargetElement``pageAction.openPopup``pageAction.show``tabs.executeScript` |
| menu-search | Illustrates how to retrieve a list of search engines and issue a search request, using search engine details added to the context menu for selected text. | `search.search``search.get``menus.create``menus.onClicked` |
| mocha-client-tests | This example shows two methods of testing an extension: running tests from within the extension, and running tests from the command line using Karma. | `runtime.onMessage``runtime.sendMessage` |
| native-messaging | Example of native messaging, including a Python application and an extension which exchanges messages with it. | `browserAction.onClicked``runtime.connectNative` |
| navigation-stats | Demonstration of the webNavigation API, showing basic stats about which pages you've visited. | `storage.local``webNavigation.onCommitted``webNavigation.onCompleted` |
| notify-link-clicks-i18n | Shows a localized notification when the user clicks on links. | `extension.getURL``i18n.getMessage``notifications.create``runtime.onMessage``runtime.sendMessage` |
| open-my-page-button | Adds a browser action icon to the toolbar. When the browser action is clicked, the add-on opens a page that was packaged with it. | `browserAction.onClicked``tabs.create` |
| page-to-extension-messaging | Demonstrates how a web page and a content script can exchange messages. Visit https://mdn.github.io/webextensions-examples/content-script-page-script-messaging.html for the demo. |  |
| permissions | Demonstrates optional permissions using the permissions API. | `browserAction.onClicked``permissions.getAll``permissions.remove``permissions.request``runtime.getURL``tabs.create` |
| private-browsing-theme | Example dynamic theme: sets a dark theme for private windows. | `theme.reset``theme.update``windows.getAll``windows.onCreated` |
| proxy-blocker | Uses the proxy API to block requests to hosts specified on a list. | `extension.getURL``proxy.onRequest``proxy.onError``storage.local``storage.onChanged` |
| quicknote | Allows the user to make quick notes by clicking a button and entering text into the resulting popup. The notes are saved in storage. | `storage.local` |
| root-cert-stats | Shows how to get details about a request's TLS connection. | `webRequest.getSecurityInfo` |
| runtime-examples | Demo of various runtime APIs. | `browserAction.onClicked``notifications.create``runtime.getManifest``runtime.onInstalled``runtime.reload` |
| selection-to-clipboard | Demonstrates how to write to the clipboard from a content script |  |
| session-state | Demonstrates how to retrieve extension-defined state from restored tabs. | `menus.create``menus.onClicked``sessions.getTabValue``sessions.setTabValue``tabs.insertCSS``tabs.onCreated``tabs.onUpdated``tabs.query` |
| store-collected-images | Demonstrates how to use the idb-file-storage library to store and manipulate files in an extension. | `browserAction.onClicked``contextMenus.create``contextMenus.onClicked``runtime.onMessage``runtime.sendMessage``tabs.create``windows.create` |
| stored-credentials | Performs basic authentication by supplying stored credentials. | `storage.local``webRequest.onAuthRequired``webRequest.onCompleted``webRequest.onErrorOccurred` |
| tabs-tabs-tabs | Demonstrates tab manipulation: opening, closing, moving, zooming tabs. | `browserAction.setBadgeBackgroundColor``browserAction.setBadgeText``tabs.create``tabs.duplicate``tabs.getZoom``tabs.move``tabs.onCreated``tabs.onMoved``tabs.onRemoved``tabs.query``tabs.reload``tabs.remove``tabs.setZoom``tabs.Tab``tabs.update` |
| theme-integrated-sidebar | A sidebar that integrates with the current theme. | `theme.getCurrent``theme.onUpdated``windows.getCurrent` |
| theme-switcher | An example of how to use the management API for themes. | `management.getAll``management.setEnabled` |
| themes | A collection of themes illustrating:* weta\_fade: a basic theme employing a single image specified in `theme_frame:`.
* weta\_fade\_chrome: the weta\_fade theme implemented with Chrome compatible manifest keys.
* weta\_tiled: a theme using a tiled image.
* weta\_mirror: a theme using multiple images and aligning those images in the header.
* animated: use of an animated PNG.
 |  |
| top-sites | Demonstration of the topSites API. | `topSites.get` |
| user-agent-rewriter | Demonstrates using the webRequest API to rewrite the User-Agent HTTP header. | `extension.getBackgroundPage``webRequest.onBeforeSendHeaders` |
| user-script-register | Illustrates how an extension can register URL-matching user scripts at runtime. | `userScripts.register``runtime.onMessage``runtime.sendMessage` |
| webpack-modules | Demonstrates how to use webpack to package npm modules in an extension. | `runtime.onMessage``runtime.sendMessage` |
| window-manipulator | Demonstrates how to manipulate windows: opening, closing, resizing windows. | `windows.create``windows.getAll``windows.getCurrent``windows.remove``windows.update``windows​.Window` |
| open-irc-links | Demonstrates the use of protocol handlers. |  |